Biological samples that can be analyzed in the laboratory can be counted as blood, urine, cerebrospinal fluid (CSF), sweat and saliva. Organizations such as the World Health Organization (WHO), Clinical and Laboratory Standards Institute (CLSI), European Clinical Chemistry and Laboratory Medicine (EFLM) publish various procedures and explain the conditions under which sample types should be taken. It is essential that samples of all body fluids except stools and urine are stored under appropriate conditions for at least 24 hours after the result is reported. However, the storage period of the test samples whose result values may change within the specified period should be decided by the relevant laboratory specialist.
In order to prevent contamination, that is to say infection, and to prevent the concentration of non-volatile substances in the blood from increasing by evaporation, the lids of the tubes must be kept closed. The sample should be kept in an upright position at room temperature for an average of 20-25 minutes until the coagulation process ends, avoiding direct sunlight. After this time, the serum should be separated from the clot by centrifugation. Changes in various parameters may occur due to hemolysis in the sample kept without centrifugation. Keeping the sample as whole blood, i.e. citrated or edtal whole blood, for a long time causes various changes in electrolyte concentrations, enzyme activity, hematology and coagulation parameters in the sample. For this reason, we can summarize what needs to be done regarding the storage of samples as follows.
For this reason, we can summarize what needs to be done regarding the storage of samples as follows.
The samples coming to the laboratory should be started to be studied immediately, not exceeding 1 hour.
Freezing blood causes hemolysis. For this reason, blood that has not been separated by centrifugation and its serum or plasma should not be frozen. The samples to be kept are kept closed in the refrigerator at +4 °C after being absolutely centrifuged.
Samples to be stored for a long time are kept closed at -20 °C in accordance with the conditions specified in the prospectus according to the characteristics of the test to be studied.
Serum or plasma should be studied within 4 hours at the latest. If it is not used, it is kept closed in the refrigerator at +4 °C.
Serum kept for more than 12-24 hours causes changes in the values of the samples even if stored at +4 °C. Therefore, it is more correct to freeze the serum, and thus many analyzes in the serum can be stored for months intact. When working with frozen serum, it is brought to room temperature.
| Test Name | 15-25 °C Storage Condition |
|---|---|
| PT * | 8 HOURS |
| APTT* | 4 HOURS |
| D Dimer** | 3 HOURS |
| Fibrinogen * | 8 HOURS |
Samples taken into a blue capped Coagulation tube should be centrifuged and stored in plasma.
Samples taken into K2Edta tubed samples should be stored as whole blood.
| Test Name | Storage Time at 2-8 °C | Storage Time at -20 °C |
|---|---|---|
| Troponin I | 2 days | 4 months |
| Mass CKMB | 2 days | 5 months |
| B-HCG | 3 days | 4 months |
Blood samples taken into the biochemistry tube for cardiac tests should be centrifuged and stored as serum.
| Test name | Storage Condition at 20-25 °C | Storage Condition at 2-8 °C | Storage Condition at -20 °C |
|---|---|---|---|
| Glucose | 2 days | 7 days | 1 month |
| Albumin | 7 days | 1 month | 5 month |
| ALP | 1 day | 7 days | 2 months |
| ALT | 3 days | 7 days | - |
| AST | 4 days | 7 days | 3 months |
| Amylase | 7 days | 7 days | 1 year |
| Calcium | 7 days | 3 weeks | 8 months |
| T. Cholesterol | - | 7 days | 3 months |
| CK | 4 hours | - | - |
| Creatinine | 7 days | 7 days | 3 months |
| CRP | 3 days | 8 days | - |
| D. Biluribin | 1 day | 7 days | 3 months |
| GGT | 7 days | 7 days | 1 year |
| NA | 1 day | 14 days | 1 year |
| K | 1 day | 7 days | 1 year |
| CL | 1 day | 7 days | 1 year |
| Iron | 7 days | 3 weeks | 1 year |
| LDH | 2 days | 4 days | - |
| Phosphorus | 1 day | 4 days | 1 year |
| T. Biluribin | 1 day | 7 days | 6 months |
| UIBC | 7 days | 3 weeks | 1 year |
| T. Protein | 6 days | 1 month | 2 months |
| TG | 2 days | 7 days | - |
| HDL | 2 days | 7 days | 3 months |
| Urea | 2 days | 7 days | - |
| Uric Acid | 3 days | 7 days | 6 months |
| RF | 24 hours | 3 days | 1 month |
| ASO | 2 days | 2 days | 6 months |
| HBA1C Whole Blood | - | 1 day | - |
| BOS Protein | - | 1 day | 6 days |
Samples taken into biochemistry blood tube should be centrifuged and stored as serum.
The samples belonging to the HbA1C test taken into the EDTA tube should be stored as whole blood as in the table.
| Test Name | Storage Time at 2-8 °C | Storage Time at -20 °C |
|---|---|---|
| AFP | 7 days | 3 months |
| Beta HCG | 3 days | 12 months |
| Ca15.3 | 5 days | 3 months |
| Ca 19.9 | 30 days | 3 months |
| Ca 125 | 5 days | 3 months |
| CEA | 7 days | 6 months |
| DHEA-S | 2 days | 2 months |
| Estradiol | 2 days | 2 months |
| Ferritin | 7 days | 12 months |
| Free PSA | 5 days | 3 months |
| Free T3 | 7 days | 1 month |
| Free T4 | 7 days (Stability of serum taken in tubes containing separating gel 48 hours at 2-8 °C) | 1 month |
| Folate | 2 days | 1 month |
| FSH | 14 days | 6 months |
| LH | 14 days | 6 months |
| Parathormone (PTH) | Serum: Stable for 8 hours at 15-25 °C, 2 days at 2-8 °C, 6 months at -20 °C. | Plasma: Stable for 2 days at 15-25 °C, 3 days at 2-8 °C, 6 months at -20 °C. |
| Progesterone | 5 days | 6 months |
| Prolactin | 14 days | 6 months |
| Total Testosterone | 7 days | 6 months |
| Total PSA | 5 days | 6 months |
| B12 vitamin | 2 days | 2 months |
| TSH | 7 days | 1 month |
| İnsulin | 2 days | 7 days |
| 25 OH D Vitamin | 12 days | 1 year |
Blood samples taken in biochemistry tubs for hormone tests should be centrifuged and stored as serum. Blood samples taken into Edta tube for PTH test should be centrifuged and stored as plasma.
Sample containing Sodium Citrate: 2 hours at 25 °C, 12 hours at 4 °C.
Hg, HTC, WBC, Leukocyte count in the sample containing EDTA: 24 hours at 23 °C, 48 hours at 4 °C.